The invention furthermore relates to a compression sleeve that is electroconductively crimped to two cables in opposite regions referred to a longitudinal direction of the compression sleeve and on an outer side has two die impressions realized adjacent to one another over the length of the compression sleeve.
The invention also relates to a method for clamping a workpiece in a hydraulic device, preferably a handheld crimping device, with a displaceable die that can be used as a clamping part and is driven by a hydraulic piston that can be displaced in a hydraulic cylinder against the force of a pull-back spring.
The invention furthermore relates to a hydraulic device, preferably a handheld crimping device, with a displaceable die that can be used as a clamping part and driven by a hydraulic piston that can be displaced in a hydraulic cylinder against the force of a pull-back spring.
Such crimping devices, crimping methods, methods for clamping a workpiece, methods for producing an electroconductively crimped compression sleeve, as well as hydraulic devices with a die that can be used as a clamping part, have already been disclosed in various forms. U.S. Pat. No. 2,968,202 A discloses a crimping device, in which only one partial piston acts upon a first crimping part during a displacement along a first partial traveling distance. Comparable prior art is also known from U.S. Pat. Nos. 2,863,346 A, 4,365,401 A and WO 02/00368 A2.
Crimping devices and crimping methods of this type are preferably used for compressing or crimping cable lugs with inserted cables. In a known crimping device disclosed in DE-A1-3235040, the contact between the crimping part and a workpiece triggers a limitation of the further traveling distance of the crimping part such that the crimping part can only be additionally displaced from the position, at which it comes in contact with the workpiece, by a certain distance. In this way, workpieces of different sizes can be crimped in an approximately uniform fashion. However, it can occur that a workpiece, which has already been crimped once, is subjected to a second crimping operation. In such instances, the crimping part also is once again displaced by a predefined distance after it comes in contact with the workpiece such that the workpiece may ultimately be destroyed. In addition, the compressive force is always identical. Consequently, smaller workpieces are typically crimped with an excessive compressive force. This may ultimately also lead to the destruction of a workpiece.
Another crimping tool is known from U.S. Pat. No. 5,195,042. In order to ensure proper crimping, a pressure sensor is provided in this case and the maximum traveling distance of the crimping part is furthermore controlled. Although a higher compressive force can be exerted upon larger workpieces to be crimped and a lower compressive force can be exerted upon smaller workpieces to be crimped, this is only possible as a function of a measurement of the workpiece to be crimped and as a result of a pressure measurement by means of a pressure sensor.
According to WO 03/084719 A1 (see also U.S. Pat. No. 7,254,982 B2, U.S. Pat. No. 7,412,868 B2 and U.S. Pat. No. 7,421,877 B2), the working piston of an electrohydraulic crimping device can initially be displaced into a holding position, in which a part may be clamped, and only then displaced into a crimping position by means of an additional actuation.
The known devices and methods are to some extent not satisfactory because they nevertheless allow operating errors with major consequences and/or have a complicated design. There likewise is a need for advantageously carrying out a crimping operation on a sleeve and cables with different diameters, as well as for disclosing a thusly crimped compression joint. Last but not least, there is a need for advantageously and gently holding a workpiece in a hydraulic device.